Wire guides are commonly used in procedures, such as angioplasty procedures, diagnostic and interventional procedures, percutaneous access procedures and radiological and neuroradiological procedures in general, to introduce a wide variety of medical devices into the vascular system or into other vessels of a human or veterinary patient. For example, wire guides are used for advancing intraluminal devices such as stent delivery catheters, balloon dilation catheters, atherectomy catheters, and the like within body lumens.
Typically, the wire guide is positioned inside the inner lumen of an introducer catheter. The wire guide is advanced out of the distal end of the introducer catheter into the patient until the distal end of the wire guide reaches the location where the interventional procedure is to be performed. After the wire guide is inserted, another device such as a stent and stent delivery catheter is advanced over the previously introduced wire guide into the patient until the stent delivery catheter is in the desired location. After the stent has been delivered, the stent delivery catheter can then be removed from a patient by retracting the stent delivery catheter back over the wire guide. The wire guide may be left in place after the procedure is completed to ensure easy access if this is required.
Peripheral chronic total occlusion (“CTO”) is a condition where an obstruction has built up in a peripheral vessel to the extent where there is no blood flow through the vessel. This blockage can lead to ischemic conditions in the extremities and commonly results in the need for invasive treatment. In these CTOs it is common for there to be a cholesterol crystal covering at each end of the occlusion. This covering exists due to macrophages accumulated in an inflammatory response and an increase in retained low-density lipoprotein LDL.
An occlusion may also result from thrombosis. Thrombosis is the formation of a thrombus, or blood clot, within the vascular system of a patient. A blood clot typically occurs when blood hardens from a liquid to a solid. When attached to vessel walls, blood clots, and other substances, such as plaque or fat, may reduce or block blood flow downstream from the clot.
The resulting blockage may prevent critical blood flow and oxygen from reaching certain tissues and, thus, may result in damage to the tissues. Regardless of the particular location of the occlusion within the vascular system, such an occlusion or, in particular, a CTO, if left untreated, may cause serious damage and, in some cases, may become life threatening.
A number of invasive and non-invasive techniques are available for treating an occlusion. These include exercise, open surgery and pharmacological methods. For example, some percutaneous techniques include the use of pharmacological agents, also referred to as thrombolytic agents, to help dissolve clots. Other percutaneous techniques may include the use of a wire guide and/or catheter to cross the occlusion and recanalize the vessel. However, crossing a CTO using a wire guide and/or catheter may be difficult and, sometimes, impossible, due to the hardness of the clot or other occlusion.
In such situations, the sub-intimal tracking and re-entry (STAR) technique allows for a bypass of the occlusion by entering the subintimal layer just before the occlusion and exiting once past the occlusion, and then stenting or ballooning open the burrowed path in the subintimal space and provide a path for blood to flow.